This ChicagoLatrobe 150L series lefthand (reverse) jobber length drill bit set contains 15 highspeed steel drill bits, including inch sizes 1/16Inches through 1/2Inches in 1/32Inches increments, with an uncoated (bright) finish and a 118degree conventional point for use on a range of materials, especially soft metals. The counterclockwise spin of the lefthand helix can be used for removing broken screws from a threaded hole or drilling in reverse direction. Highspeed steel (HSS) provides hardness for wear resistance, and the uncoated finish provides an untreated surface. A jobber length drill bit has a versatile midrange drilling depth that is a common choice for a range of drilling applications. The round shank accommodates most drill chucks.The set comes in a gray epoxycoated steel index case with labeled compartments for identification and organization. Case measures 73/8 x 41/4 x 11/4 inches (H x W x D). (H is height, the vertical distance from lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back.)Drill bits are cutting tools used to make holes in a range of materials using machines such as handheld portable drills, machining centers, and lathes. Drill bits come in a variety of lengths and types, the most common of which is the twist drill bit. The round, twisted shaft of the twist drill bit typically has two cutting edges and flutes. The helical twist of the flutes brings chips up and away from the cutting edges and allows for coolant to reach the cutting edges. Jobber length twist drill bits, the most common length of twist drill bit, offer a good compromise of length and reach to work with the widest range of materials and applications. Mechanics length twist drill bits (also called maintenance length) are a little shorter than jobber length and less prone to deflection when drilling. Short length twist drill bits (also called stub or screwmachine length) are the shortest and stiffest twist drill bits, helping to reduce the chance of deflection or breakage when drilling. Reduced shank drill bits (also called Silver and Deming drill bits) have a shank that is smaller in diameter than its shaft, permitting drilling machines with either a 1/2Inches or 3/4Inches drill chuck to create large holes. Long length twist drill bits (also called taper length) are a little longer than jobber length, allowing for deeper holes and longer reach. Extra long twist drill bits (also called extension) are longer than long length twist drill bits for greater reach or for drilling deeper holes.ChicagoLatrobe manufactures drill bits and accessories, reamers, countersinks, and blanks. The company, founded in 1890 and headquartered in Clemson, SC, meets International Organization for Standardization (ISO) standard 9001.Whats in the Box? 15 drill bits, inch sizes 1/16Inches through 1/2Inches in 1/32Inches increments Steel case